Apparatus for transmitting or reproducing sound



Aug. 16,1927.

S. G. BROWN APPARATUS FOR TRANSMITTING OR EPRODCING SOUND Filed June 29. 192s Patemea Aug. 1e, 1927.

` UNITED STATES- SIDNEY GEORGE BROWN, OF NORTH ACTON, LONDON, ENGLAND.

v1,639,583 PATENT OFFICE.

APPARATUS FOR TRANSHITTING OR REPRODUCING SOUND.

Application led June 29, 1926, Serial No. 119,496, and in Great Britain September 19, 1925.

This invention relates to apparatus for transmitting or reproducing sound, more particularly telephone receivers.

In telephone receivers used for wireless it is common to provide for adjustment of the air gap between the magnet pole pieces and the armature.

The object of the invention is' to improve such means of adjustment.

The invention consists in the improved phonic apparatus hereinafter 'described and more particularly pointed out in the claims. Referring to the accompanying drawings Figure 1 shows an elevation with the cover and diaphragm remove-d ofa telephone receiver ear-piece,

Figure 2 being a corresponding sectional elevation;

Figure 3 is a view looking on the back of Figure 1 with the casing removed, and

Figure 4 a perspective View showing the attachment of the pole pieces and bridge.

In, carrying the invention into eii'ect according to one form as applied by way of example to a telephone receiver ear-piece of the vibrating-reed type, the magnetsare formed of two stampings, a, b, semi-circular in shape with the centre portion remove-d. These are secured with their ends together by means of screws, c, c, to a brass back plate, d, which overlaps the two joints. The pole pieces, e, e, on which are mounted the usual coils, f, j, are secured tothe magnets,

a, b, at their joints by means of the screws,

c, c. These two pole pieces butt towards one another at thefcentre leaving a small gap, h, (see Figure 4) between them, Over this gap is secured the reed, .15, by means of a screw, le, passing through one of said mag= nets, the reed in turnbeing attached to the diaphragm, 111. The two pole pieces on the opposite side to the reed are secured by any suitable fastening means, m, m, to a bridge or yokepiece,"n, of thin brass or other nonmagnetic material which has its two ends bent into feet which are'moimted by means of screws, p, p, on a solid piece ofv brass, 0 orother non-magnetic vmaterial in the centre of which is tapped a hole. A reed stop, r, may be provided upon this brass piece.

The magnets are secured to the casing, s, by means of two screws, t, @situated one on each side of the reed and assed through one of the magnets, a, the bac plate, d, and

the casing, s, and secured at the other end s ployed.

bend about their two ends secured to thev magnets, the thin brass bridge or yoke-piece, n, being also slightly deformed.

It will thus be seen that the magnets are rigidly secured to the casing'and that the pole. pieces are secured to the magnet but at the same time are deformable by means of the milled nut at the back of the casing, thus providing means for adjusting the air gap Y between the reed or armature and the pole pieces of the magnet, while maintaming rigidity of support for the pole pieces. The invention is applicable to any type of apparatus for transmitting or reproducing soundin which a vibrating element is em- I-Iaving now described my invention what I claim as newcand desire to secure byv Let ters Patent ist- 1. In phonic apparatus the combination comprising an electro-magnet having pole pieces with an air gap therebetween, a iiexible non-magnetic yoke piece mounted upon vand bridging the gap between said pole pieces, a rigid member supporting said yoke piece, an armature situated over said a1r gap and means attached to said rigid member for bending said yoke piece together with said pole pieces towards and away from said armature, as set forth.

2. In phonic apparatus the`combination comprising magnets having pole pieces with an air gap therebetween, a flexible non-mag- A netic yoke 'piece mounted upon and bridging the gap between said pole pieces, windings surrounding said pole' pieces and portions of said yoke piece, lugs projecting from said yoke piece, a non-magnetic rigid member attached to said lugs, and means attached to said rigid member for bending said yoke piece together with sai-d -pole pieces relatively to said magnet, as set forth.

3. Phonic apparatus as claimed 1n clalm l, in which the rigid member is provided with an adjustable stop to prevent the armature from making contact with the pole flexible non-magnetic yoke piece m'urted pieces, as set forth. upon said pole pieces. and bridgin thei-'a'ir 4. Phonic apparatus as claimed in claim gap on the opposite side to said ree a rigid 2, in which the rigid memberis in the form member attached to said yoke piece, and 15 5 of a strip and is arranged transversely of means attached to' said rigid member for the pole pieces. bending said yoke piece together With said 5. A telephone receiver comprising in compole pieces-towards and away from said reed. bination, an electro-magnet having pole Iny testimony whereof-I havel signed my pieces with an air gap therebetween, a ree-d name to this speciication. 10 adapted to vibrate vmounted over said air gap, a diaphragm attached to said reed, a SIDNEYG'EORGE BROWN. 

